Is it fair to say that Leonardo’s Last Supper still exists after an expensive 20-year restoration? The images are still so faded out[U of Chicago Press] and the dim conditions under which they can be seen in person so uncomfortable, that the painting scarcely resembles what Leonardo must have intended.

After the Louvre restored a prominent painting by Veronese last year, an expert despaired[The Times (London)] at what had been done: "Clothes that were originally red were now green. The whole spatial and wonderful chromatic harmony is distorted. When you look at the painting . . . black, red and blue colors seem to be floating among other colors like pieces of a broken puzzle. The light is now a cold, artificial, modern one."

India's Ajanta paintings, which easily rank among the world’s most precious heritage sites, are being restored [The Art Newspaper]. But a leading expert warns that "the cleaning methods employed at the caves and the level of skills of the workers engaged in the cleaning have seriously damaged the Ajanta paintings and led to a demonstrable loss of pigment."

When the Vatican's St. Peter's got a facelift two years ago, restoring some original color to the façade, critics decried the job as a post-modern hash, born out of a “desire to transform everything into a movie set."

Last year a minor scandal of sorts erupted at the British Museum when it was revealed [The Art Newspaper] that when the museum’s experts cleaned the Elgin marbles back in the 1930s they irreparably damaged them.

Unpleasant surprises and occasionally acrimonious disputes like these provide public glimpses of the state of mind of a discipline whose self-examination just now is wide, deep, and intense. At the risk of gross oversimplification, that self-examination centers on two major issues.

1.Quality of Conservation

Among the matters that conservators disagree about is who should be regarded as a conservator in the first place[The Telegraph]. In Italy, despite a decades-old law to the contrary, “any Italian citizen can be registered as a restorer, and get working on ‘improving’ a supreme work of art—whether he or she has had any training or not,” according to distinguished (and distressed) art historian and restorer Bruno Zanardi. The result: Italy, with the world’s greatest concentration of master works in need of conservation and with a comparably large pool of conservation expertise, is a scene of conservation chaos.

But disagreement scarcely stops at the question of credentials and qualifications. When five conservators met for a conversation[Getty Conservation Newsletter] about surface cleaning sponsored by the Getty Conservation Institute, the results were revealing. What counts as best practice in Old Masters painting conservation may not be so regarded in antiquities conservation.

Similarly, a conservator of fine furniture may draw the line between restoration and preservation very differently than do his colleagues either in antiquities or in painting. (Getty Conservation Institute Newsletter).

The layman may assume that in a painting soil is the top layer, shellac or varnish the middle layer(s), and paint the bottom layer(s), but scientific cross-section studies by Richard Wolbers show clear and sobering layer-to-layer vertical migration[Getty]. It might not be possible, then, to remove the shellac without removing some of the paint.

Furthermore, though dirt may have no rights, shellac does. The older the work, the more art-historical information is to be recovered from whatever may have been applied to its surface in the past. Patinas and glazes have a story to tell, in short, and paintings that show signs of conservation are less valuable, other things equal, than those that show none.

The research science of conservation clearly complicates rather than simplifies the lives of working conservators. Research chemists told a meetingAnanova] of the American Chemical Society that the solvents which many collectors and curators use to clean paintings often damage the paint, first softening and deforming it, then—when the solvent dries—rendering it more brittle and fragile. The chemists proposed using sophisticated computer models to predict paint behavior under cleaning.

But how many museums can afford computer modeling, and where does this process end? The science of “art defense,” like the science of military defense, makes everything more expensive, so much so that at least a few voices have begun to ask about bang for the buck.

2.Politics of Conservation

Padua’s Scrovegni Chapel recently unveiled its restored Giotto frescoes, but they sit climate-controlled, under glass while strictly monitored visitors struggle to get a glimpse. The Atlantic’s Francine Prose described such an unpleasant experience trying to see the art that she wondered: “Maybe we should at least consider the radical notion that masterpieces—like so much else in this mutable world—have a life-span, and ask ourselves if preserving them is worth making it so unpleasant to experience them.”

Certainly Leonardo’s Last Supper, though officially restored and open again to the public, should be spoken of in the past tense. Essentially, the work no longer exists, and reading a learned account of its restoration in a sumptuous book [U of Chicago Press] may well be more rewarding than squinting at the depressing little that remains of the thing itself in the refectory of the Santa Maria delle Grazie monastery in Milan.

Bruno Zanardi raises an adjacent objection: Heavy expenditure on tourist attractions like the Last Supper and the Scrovegni Chapel, some of it made necessary by the tourists themselves, is robbing thousands of off-the-beaten-track masterpieces of the pennies that would make basic maintenance possible. “There’s no [Italian government] interest at all,” he laments, “in the thousands of buildings and churches that are quietly crumbling, along with the objects inside them, in the centers of Italy’s ancient cities”[The Telegraph].

Prose’s meditation on the virtually embalmed frescoes reminds one of the school of thought that says that endangered species should not be kept in zoos but left in their natural habitat and that humans should be content to view them on film or in museums.

As an alternative to the quasi-taxidermy of the Scrovegni Chapel, she reports “talk of erecting a facsimile of the chapel and the frescoes—rather like the faux version of the cave paintings at Lascaux—that tourists could visit in lieu of the real thing. But why would anyone want to? Wouldn’t most people prefer just to stay home [The Atlantic] and contemplate, at their leisure, reproductions of the frescoes in an art book or on a computer screen?”

Good question. But what serious art lover would suggest that a poster or book or computer-screen representation of a work of art compares to experiencing the original? Just how many tourists would visit a full-size Scrovegni Chapel facsimile remains to be seen. Perhaps a great many would.

Theme park operators such as Disney have made billions proving there is a vast audience for places that are supposed to be other places. Such recreations, architecture critic Ada Louise Huxtable has pointed out, often seek to recreate an experience that probably never existed – instead substituting our imaginings of what an idealized place or thing might have been.

Worse, the theme-park mentality as applied to conservation can be downright dangerous. “Restoration” of sites such as Ephesus in Turkey, old Samarkand, and now Old Bukhara[CNN] risks turning them into little more than walkabout fantasies for the tourist trade, in the process destroying the historical (as distinct from artistic) value of what was originally there.

A more contemporary example is the perpetually cash-strapped Barnes Collection outside Philadelphia. One proposal to revive the Barnes’ fortunes is to recreate it downtown in a more tourist-friendly location. That, it has been pointed out,[Philadelphia Inquirer] might be good for the bottom line, but the distinctive experience of the Barnes as directed by its founder would most certainly be lost.

On the other hand, the case for facsimiles may be strong for books and precious manuscripts. While the technology for the preservation of, for example, J.S. Bach autographs is progressing dramatically[CNN], so is digital photography that can sometimes “see” more than the naked eye can. CD-ROM facsimiles provide, on the one hand, a uniquely private and functional experience of rare books or manuscripts and, on the other, minimize damage to fragile works that, uniquely, cannot be seen without being touched.

Paradoxically, however, the very iconization of original objects, monuments and buildings which makes them valued objects of restoration can subvert their intended effect. Celebrating the creation of the Last Supper is one thing; fetishizing its ghostly shadow is something else. No wonder some of the best minds in the art world are discovering the tao of conservation—cultivated skepticism about their own best efforts.